In mechanics, different components often move in contact with respect to each other to transmit power or motion; tribology is the study of this topic. One example of moving components may be the rotation of engaged gears and, more particularly, the relative motion of the intermeshing teeth of the gears. As is known, relative motion between interacting components may result in friction and wear. Friction and the resulting wear depend upon the load conditions and relative velocity of the components and can be classified according to different characteristics. Examples of wear characteristics include adhesion in which the minute contact points create localized adhesive bonds that destructively detach when relative motion occurs and abrasion in which asperities of one surface cut through the other surface. To reduce friction and wear, lubrication is often provided between the moving components. Many different types of lubrication exist including greases, oils, and dry lubricants such as powdered graphite. Different lubricants have different characteristics and may come in different grades and, accordingly, some lubricants may be better suited for certain conditions than other lubricants.
To test the wear conditions and/or the suitability of various lubricants for those conditions, a test apparatus may be constructed to simulate the relative motion of parts. One example of a test apparatus is disclosed in U.S. Pat. No. 5,388,442 (“the '442 patent”), assigned to Tranergy Corp. The '442 patent describes a machine which includes a powered wheel and a freely rotating wheel which are placed adjacent each other in a single point of contact along their circular surfaces. The powered wheel can be driven by a motor to rotate with respect to the free wheel, the rotation of which may be adjustably constrained by a brake to mimic various rolling and/or sliding conditions. Lubrication can be introduced between the wheels and a load cell while transducers, visual inspection, and the like can measure its affect. The present disclosure is also directed to a machine for simulating different load and wear conditions and/or testing lubricants.